‘Change is the only constant thing in the world.” The invention of the computer resulted in wanting more better computers and greater and advanced features. The same goes on for IoT. The Internet of Things also known as IoT is the ultimate building block for smart objects. A search for better and environmentally sound function resulted in Green IoT. A Smart city comprises all the basic necessities but in a smarter version. From the bed light before sleeping to the automated alarm to wake one up. Everyone is surrounded by Smart objects. These objects have definitely made our life easier. However, a change in life may have both good and bad consequences. Despite the benefits of IoT, energy consumption is still on the rise. This problem brought the solution motivated by achieving a sustainable smart city incorporated with Green IoT. This not only saves the extra energy which it was utilized priorly by IoT but also works efficiently. The Green IoT is a new advancement in technology and this paper discusses the merits, demerits, and various recommendations.